TY - JOUR A1 - Szymoniak, Paulina A1 - Pauw, Brian Richard A1 - Qu, Xintong A1 - Schönhals, Andreas T1 - Competition of nanoparticle-induced mobilization and immobilization effects on segmental dynamics of an epoxy-based nanocomposite N2 - The complex effects of nanoparticles on a thermosetting material based on an anhydride cured DGEBA/Boehmite nanocomposite with different particle concentrations is considered. A combination of X-ray scattering, calorimetry, including fast scanning calorimetry as well as temperature modulated calorimetry and dielectric spectroscopy, was employed to study the structure, the vitrification kinetics and the molecular dynamics of the nanocomposites. For the first time in the literature for an epoxy-based composite a detailed analysis of the X-ray data was carried out. Moreover, the unfilled polymer was found to be intrinsically heterogeneous, showing regions with different crosslinking density, indicated by two separate dynamic glass transitions. The glass transition temperature decreases with increasing nanoparticle concentration, resulting from a change in the crosslinking density. Moreover, on the one hand, for nanocomposites the incorporation of nanofiller increased the number of mobile segments for low nanoparticle concentrations, due to the altered crosslinking density. On the other hand, for higher loading degrees the number of mobile segments decreased, resulting from the formation of an immobilized interphase (RAF). The simultaneous mobilization and immobilization of the segmental dynamics cannot be separated unambiguously. Taking the sample with highest number of mobile segments as reference state it was possible to estimate the amount of RAF. KW - Nanocomposite PY - 2020 DO - https://doi.org/10.1039/d0sm00744g SN - 1744-683X VL - 16 IS - 23 SP - 5406 EP - 5421 PB - Royal Chemical Society AN - OPUS4-50883 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Qu, Xintong A1 - Abbasi, M. A1 - Pauw, Brian Richard A1 - Henning, S. A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schick, C. A1 - Saalwächter, K. A1 - Schönhals, Andreas T1 - Spatial inhomogeneity, Interfaces and Complex Vitrification Kinetics in a Network Forming Nanocomposite N2 - A detailed calorimetric study on an epoxy-based nanocomposite system was performed employing bisphenol A diglycidyl ether (DGEBA) cured with diethylenetriamine (DETA) as the polymer matrix and taurine-modified MgAL layered double hydroxide (T-LDH) as nanofiller. The -NH2 group of taurine can react with DGEBA improving the interaction of the polymer with the filler. The combined X-ray scattering, and electron microscopy data showed that the nanocomposite has a partially exfoliated morphology. Calorimetric studies were performed with conventional DSC, temperature modulated DSC (TMDSC) and fast scanning calorimetry (FSC) in the temperature modulated approach (TMFSC) to investigate the vitrification and molecular mobility in dependence of the filler concentration. First, TMDSC and NMR were used to estimate the amount of the rigid amorphous fraction which consists of immobilized polymer segments at the nanoparticle surface. It was found to be 40 wt% for the highest filler concentration, indicating that the interface dominates the overall macroscopic properties and behavior of the material to a great extent. Second, the relaxation rates of the α-relaxation obtained by TMDSC and TMFSC were compared with the thermal and dielectric relaxation rates measured by static FSC. The investigation revealed that the system shows two distinct α-relaxation processes. Furthermore, also two separate vitrification mechanisms were found for a bulk network-former without geometrical confinement as also confirmed by NMR. This was discussed in terms of the intrinsic spatial heterogeneity on a molecular scale, which becomes more pronounced with increasing nanofiller content. KW - Polymer based Nanocomposites PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523199 DO - https://doi.org/10.1039/d0sm01992e SN - 1744-6848 VL - 17 IS - 10 SP - 2775 EP - 2790 PB - Royal Society of Chemistry AN - OPUS4-52319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fahmy, Alaa A1 - Omar, Hassan A1 - Szymoniak, Paulina A1 - Schönhals, Andreas A1 - Friedrich, J. T1 - Structure of plasma deposited acrylic acid‐allyl alcohol copolymers N2 - Copolymer thin films with two types of functional groups have excellent performance as sensors, for example. The formation and deposition of allyl alcohol‐acrylic acid copolymer films by pulsed high frequency plasma is a complex process. As usual, the chemical composition of the top surface of the films was investigated by XPS and FTIR measurements. Furthermore, contact angle measurements with water were used to characterise the hydrophilicity and wettability of the polymer films. After plasma deposition, a significant decrease in functional groups (OH and COOH) was observed compared to the classically copolymerised equivalent. The remaining functional groups, i.e. the majority of these groups, were sufficient for application as sensor layers. Segmental mobility and conductivity, important for sensor applications, were analysed by broadband dielectric spectroscopy. KW - Plasma Polymerization PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-578349 DO - https://doi.org/10.1002/ppap.202300071 SN - 1612-8850 SP - 1 EP - 14 PB - Wiley online library AN - OPUS4-57834 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, Guiping A1 - Liu, Ye A1 - Schultz, Thorsten A1 - Exner, Moritz A1 - Muydinov, Ruslan A1 - Wang, Hui A1 - Scheurell, Kerstin A1 - Huang, Jieyang A1 - Szymoniak, Paulina A1 - Pinna, Nicola A1 - Koch, Norbert A1 - Adelhelm, Philipp A1 - Bojdys, Michael J. T1 - One‐Pot Synthesis of High‐Capacity Sulfur Cathodes via In‐Situ Polymerization of a Porous Imine‐Based Polymer N2 - AbstractLithium‐ion batteries, essential for electronics and electric vehicles, predominantly use cathodes made from critical materials like cobalt. Sulfur‐based cathodes, offering a high theoretical capacity of 1675 mAh g−1 and environmental advantages due to sulfur's abundance and lower toxicity, present a more sustainable alternative. However, state‐of‐the‐art sulfur‐based electrodes do not reach the theoretical capacities, mainly because conventional electrode production relies on mixing of components into weakly coordinated slurries. Consequently, sulfur‘s mobility leads to battery degradation—an effect known as the “sulfur‐shuttle”. This study introduces a solution by developing a microporous, covalently‐bonded, imine‐based polymer network grown in situ around sulfur particles on the current collector. The polymer network (i) enables selective transport of electrolyte and Li‐ions through pores of defined size, and (ii) acts as a robust host to retain the active component of the electrode (sulfur species). The resulting cathode has superior rate performance from 0.1 C (1360 mAh g−1) to 3 C (807 mAh g−1). Demonstrating a high‐performance, sustainable sulfur cathode produced via a simple one‐pot process, our research underlines the potential of microporous polymers in addressing sulfur diffusion issues, paving the way for sulfur electrodes as viable alternatives to traditional metal‐based cathodes. KW - In-situ polymerization KW - Sulfur cathodes PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604215 DO - https://doi.org/10.1002/anie.202400382 SN - 1433-7851 SP - 1 EP - 11 PB - Wiley VHC-Verlag AN - OPUS4-60421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yildirim, Arda A1 - Szymoniak, Paulina A1 - Sentker, K. A1 - Butschies, M. A1 - Bühlmeyer, A. A1 - Huber, P. A1 - Laschat, S. A1 - Schönhals, Andreas T1 - Dynamics and ionic conductivity of ionic liquid crystals forming a hexagonal columnar mesophase N2 - For the first time, the molecular mobility of two linear-shaped tetramethylated guanidinium triflate ionic liquid crystals (ILCs) having different length of alkyl chains were investigated by a combination of broadband dielectric spectroscopy (BDS) and specific heat spectroscopy (SHS). By self-assembly, these ILCs can form a hexagonal ordered mesophase besides plastic crystalline phases and the isotropic state. Three dielectric active processes were found by BDS for both samples. At low temperatures, a γ-process in the plastic crystalline state is observed which is assigned to localized fluctuations of methyl groups including nitrogen atoms in the guanidinium head. At higher temperatures but still in the plastic crystalline state, an α1-process takes place. An α2 process was detected by SHS but with a completely different temperature dependence of the relaxation times than that of the α1-relaxation. This result is discussed in detail, and different molecular assignments of the processes are suggested. At even higher temperatures, electrical conductivity is detected and an increase in the DC conductivity by four orders of magnitude at the phase transition from the plastic crystalline to the hexagonal columnar mesophase is found. This result is traced to a change in the charge transport mechanism from a delocalized electron hopping in the stacked aromatic systems (in the plastic phase) to one dominated by an ionic conduction in the quasi-1D ion channels formed along the supermolecular columns in the ILCs hexagonal mesophases. KW - Ionic liquid crystalls PY - 2018 DO - https://doi.org/10.1039/c7cp08186c SN - 1463-9084 SN - 1463-9076 VL - 20 IS - 8 SP - 5626 EP - 5635 PB - Royal Society of Chemistry AN - OPUS4-44254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madkour, Sherif A1 - Szymoniak, Paulina A1 - Hertwig, Andreas A1 - Heidari, M. A1 - von Klitzing, R. A1 - Napolitano, S. A1 - Sferrazza, M. A1 - Schönhals, Andreas T1 - Decoupling of dynamic and thermal glass transition in thin films of a PVME/PS blend N2 - The discussions on the nanoconfinement effect on the glass transition and glassy dynamics phenomena have yielded many open questions. Here, the thickness dependence of the thermal glass transition temperature of thin films of a PVME/PS blend is investigated by ellipsometry. Its thickness dependence was compared to that of the dynamic glass transition (measured by specific heat spectroscopy), and the deduced Vogel temperature (T0). While and T0 showed a monotonous increase, with decreasing the film thickness, the dynamic glass transition temperature () measured at a finite frequency showed a non-monotonous dependence that peaks at 30 nm. This was discussed by assuming different cooperativity length scales at these temperatures, which have different sensitivities to composition and thickness. This non-monotonous thickness dependence of disappears for frequencies characteristic for T0. Further analysis of the fragility parameter, showed a change in the glassy dynamics from strong to fragile, with decreasing film thickness. KW - Thin polymeric films KW - Ellipsometry KW - Specific heat spectroscopy PY - 2017 DO - https://doi.org/10.1021/acsmacrolett.7b00625 SN - 2161-1653 VL - 6 IS - 10 SP - 1156 EP - 1161 PB - ACS Publications AN - OPUS4-42266 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Ahmadi, Shayan A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Molecular Mobility of Thin Films of Poly (bisphenol-A carbonate) Capped and with one Free Surface: From Bulk-like Samples down to the Adsorbed Layer N2 - The molecular mobility of thin films of poly(bisphenol A carbonate) (PBAC) was systematically investigated using broadband dielectric spectroscopy, employing two distinct electrode configurations. First, films were prepared in a capped geometry between aluminum electrodes employing a crossed electrode capacitor (CEC) configuration, down to film thicknesses of 40 nm. The Vogel temperature, derived from the temperature dependence of relaxation rate of the α-relaxation, increases with decreasing film thickness characterized by an onset thickness. The onset thickness depends on the annealing conditions, with less intense annealing yielding a lower onset thickness. Additionally, a broadening of the β-relaxation peak was observed with decreasing thickness, attributed to the interaction of phenyl groups with thermally evaporated aluminum, resulting in a shift of certain relaxation modes to higher temperatures relative to the bulk material. A novel phenomenon, termed the slow Arrhenius process (SAP), was also identified in proximity to the α-relaxation temperature. For films with thicknesses below 40 nm, nanostructured electrodes (NSE) were utilized, incorporating nanostructured silica spacers to establish a free surface with air. This free surface causes an enhancement in the molecular mobility for the 40 nm sample, preserving the β-relaxation as a distinct peak. The α-relaxation was detectable in the dielectric loss down to 18 nm, shifting to higher temperatures as film thickness is decreased. Notably, the onset thickness for the increase in Vogel temperature was lower in the NSE configuration compared to the CEC setup, attributed to the presence of the polymer-air interface. KW - Thin polymer films PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623422 DO - https://doi.org/10.1039/d4sm01238k SN - 1744-6848 VL - 21 IS - 2 SP - 241 EP - 254 PB - RSC AN - OPUS4-62342 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Hiid, Gundula A1 - Szymoniak, Paulina A1 - Hertwig, Andreas A1 - Schönhals, Andreas T1 - Growth kinetics of the adsorbed layer of poly(bisphenol A carbonate) and its effect on the glass transition behavior in thin films N2 - The glass transition behavior of thin films of poly(bisphenol A carbonate) (PBAC) was studied employing ellipsometry. The glass transition temperature increases with the reduction of the film thickness. This result is attributed to the formation of an adsorbed layer with a reduced mobility compared to bulk PBAC. Therefore, for the first time, the growth kinetics of the adsorbed layer of PBAC was investigated, prepared by leaching samples from a 200 nm thin film which were annealed for several times at three different temperatures. The thickness of each prepared adsorbed layer was measured by multiple scans using atomic force microscopy (AFM). Additionally, an unannealed sample was measured. Comparison of the measurements of the unannealed and the annealed samples provides proof of a pre-growth regime for all annealing temperatures which was not observed for other polymers. For the lowest annealing temperature after the pre-growth stage only a growth regime with a linear time dependence is observed. For higher annealing temperatures the growth kinetics changes from a linear to a logarithmic growth regime at a critical time. At the longest annealing times the films showed signs of dewetting where segments of the adsorbed film were removed from the substrate (dewetting by desorption). The dependence of the surface roughness of the PBAC surface on annealing time also confirmed that the films annealed at highest temperatures for the longest times desorbed from the substrate. KW - Ultra thin polymer films PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574531 DO - https://doi.org/10.1039/D3RA02020G SN - 2046-2069 VL - 13 IS - 21 SP - 14473 EP - 14483 PB - RSC Publishing CY - London AN - OPUS4-57453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kimiaei, E. A1 - Farooq, M. A1 - Szymoniak, Paulina A1 - Ahmadi, Shayan A1 - Babaeipour, S. A1 - Schönhals, Andreas A1 - Österberg, M. T1 - The role of lignin as interfacial compatibilizer in designing lignocellulosic-polyester composite films N2 - Advancing nanocomposites requires a deep understanding and careful design of nanoscale interfaces, as interfacial interactions and adhesion significantly influence the physical and mechanical properties of these materials. This study demonstrates the effectiveness of lignin nanoparticles (LNPs) as interfacial compatibilizer between hydrophilic cellulose nanofibrils (CNF) and a hydrophobic polyester, polycaprolactone (PCL). In this context, we conducted a detailed analysis of surface-to-bulk interactions in both wet and dry conditions using advanced techniques such as quartz crystal microbalance with dissipation (QCM-D), atomic force microscopy (AFM), water contact angle (WCA) measurements, broadband dielectric spectroscopy (BDS), and inverse gas chromatography (IGC). QCM-D was employed to quantify the adsorption behavior of LNPs on CNF and PCL surfaces, demonstrating LNPs’ capability to interact with both hydrophilic and hydrophobic phases, thereby enhancing composite material properties. LNPs showed extensive adsorption on a CNF model film (1186 ± 178 ng.cm−2) and a lower but still significant adsorption on a PCL model film (270 ± 64 ng.cm−2). In contrast, CNF adsorption on a PCL model film was the lowest, with a sensed mass of only 136 ± 35 ng.cm−2. These findings were further supported by comparing the morphology and wettability of the films before and after adsorption, using AFM and WCA analyses. Then, to gain insights into the molecular-level interactions and molecular mobility within the composite in dry state, BDS was employed. The BDS results showed that LNPs improved the dispersion of PCL within the CNF network. To further investigate the impact of LNPs on the composites’ interfacial properties, IGC was employed. This analysis showed that the composite films containing LNPs exhibited lower surface energy compared to those composed of only CNF and PCL. The presence of LNPs likely reduced the availability of surface hydroxyl groups, thus modifying the physicochemical properties of the interface. These changes were particularly evident in the heterogeneity of the surface energy profile, indicating that LNPs significantly altered the interfacial characteristics of the composite materials. Overall, these findings emphasize the necessity to control the interfaces between components for next-generation nanocomposite materials across diverse applications. KW - Lignin KW - Nanocomposites PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615098 DO - https://doi.org/10.1016/j.jcis.2024.10.083 SN - 0021-9797 VL - 679 SP - 263 EP - 275 PB - Elsevier Inc. AN - OPUS4-61509 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Xu, Q. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Yang, Z. A1 - Wang, S. A1 - Gao, Y. A1 - Shang, J. A1 - Hunger, J. A1 - Aldiyarov, A. A1 - Schönhals, Andreas A1 - Ge, Y. A1 - Qi, Z. T1 - Molecular engineering of supramolecular polymer adhesive with confined water and a single crown ether N2 - Here, we report a water-induced supramolecular polymer built from confined structural water and an intrinsic amphiphilic macrocyclic self-assembly in a nanophase separated structure. The newly designed crown ether macrocycle, featuring strong hydrophilic hydrogen bonding receptor selenoxide and a synergistical hydrophobic selenium-substituted crown core, confines the structural water in a segregated, interdigitated architecture. Although water molecules typically freeze around 0 °C, the confined structural water in this supramolecular polymer remains in a liquid-like state down to 80 °C. Previous studies suggest that multiple crown ether units are needed to generate structural water. However, here, one unit is sufficient to control the formation and disappearance of structural water and consequent supramolecular polymerization. Typically, the DC conductivity of water shows Arrhenius temperature dependency (lnσDC ∝ 1/T). In contrast, this new crown unit maintains water in confined states, which exhibit a Vogel/Fulcher/Tammann behavior (lnσDC ∝ 1/(T-T0)) at temperatures above the glass transition temperature. Moreover, this water-induced supramolecular polymer exhibits remarkable adhesion properties to hydrophilic surfaces and maintains tough adhesion at low temperatures. These findings show how a single small macrocycle can govern the complex structure and functionality of water in supramolecular systems. KW - Supramolecular polymerization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623631 DO - https://doi.org/10.1039/D4SC06771A SN - 2041-6539 VL - 16 SP - 1 EP - 9 PB - RSC AN - OPUS4-62363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Ahamadi, Shayan A1 - Hülagü, Deniz A1 - Hidde, Gundula A1 - Hertwig, Andreas A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Investigations of the adsorbed layer of polysulfone: Influence of the thickness of the adsorbed layer on the glass transition of thin films N2 - This work studies the influence of the adsorbed layer on the glass transition of thin films of polysulfone. Therefore, the growth kinetics of the irreversibly adsorbed layer of polysulfone on silicon substrates was first investigated using the solvent leaching approach, and the thickness of the remaining layer was measured with atomic force microscopy. Annealing conditions before leaching were varied in temperature and time (0–336 h). The growth kinetics showed three distinct regions: a pre-growth step where it was assumed that phenyl rings align parallel to the substrate at the shortest annealing times, a linear growth region, and a crossover from linear to logarithmic growth observed at higher temperatures for the longest annealing times. No signs of desorption were observed, pointing to the formation of a strongly adsorbed layer. Second, the glass transition of thin polysulfone films was studied in dependence on the film thickness using spectroscopic ellipsometry. Three annealing conditions were compared: two with only a tightly bound layer formed in the linear growth regime and one with both tightly bound and loosely adsorbed layers formed in the logarithmic growth regime. The onset thickness and increase in the glass transition temperature increases with annealing time and temperature. These differences were attributed to the distinct conformations of the formed adsorbed layers. KW - Glass transition KW - Adsorbed Layer PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607701 DO - https://doi.org/10.1063/5.0223415 SN - 0021-9606 VL - 161 IS - 5 SP - 1 EP - 12 PB - AIP Publishing AN - OPUS4-60770 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madkour, Sherif A1 - Szymoniak, Paulina A1 - Schick, Ch. A1 - Schönhals, Andreas T1 - Unexpected behavior of ultra-thin films of blends of polystyrene/poly(vinyl methyl ether) studied by specific heat spectroscopy N2 - Specific heat spectroscopy (SHS) employing AC nanochip calorimetry was used to investigate the glassy dynamics of ultra-thin films (thicknesses: 10 nm–340 nm) of a polymer blend, which is miscible in the bulk. In detail, a Poly(vinyl methyl ether) (PVME)/Polystyrene (PS) blend with the composition of 25/75 wt. % was studied. The film thickness was controlled by ellipsometry while the film topography was checked by atomic force microscopy. The results are discussed in the framework of the balance between an adsorbed and a free surface layer on the glassy dynamics. By a self-assembling process, a layer with a reduced mobility is irreversibly adsorbed at the polymer/substrate interface. This layer is discussed employing two different scenarios. In the first approach, it is assumed that a PS-rich layer is adsorbed at the substrate. Whereas in the second approach, a PVME-rich layer is suggested to be formed at the SiO2 substrate. Further, due to the lower surface tension of PVME, with respect to air, a nanometer thick PVME-rich surface layer, with higher molecular mobility, is formed at the polymer/air interface. By measuring the glassy dynamics of the thin films of PVME/PS in dependence on the film thickness, it was shown that down to 30 nm thicknesses, the dynamic Tg of the whole film was strongly influenced by the adsorbed layer yielding a systematic increase in the dynamic Tg with decreasing the film thickness. However, at a thickness of ca. 30 nm, the influence of the mobile surface layer becomes more pronounced. This results in a systematic decrease in Tg with the further decrease of the film thickness, below 30 nm. These results were discussed with respect to thin films of PVME/PS blend with a composition of 50/50 wt.%as well as literature results. KW - Ultra thin polymer films PY - 2017 DO - https://doi.org/10.1063/1.4978505 SN - 0021-9606 SN - 1089-7690 VL - 146 IS - 20 SP - 203321-1 EP - 203321-9 PB - AIP Publishing AN - OPUS4-39558 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madkour, Sherif A1 - Szymoniak, Paulina A1 - Heídari, M. A1 - von Klitzing, R. A1 - Schönhals, Andreas T1 - Unveiling the dynamics of self-assembled layers of thin films of poly(vinyl methyl ether) (PVME) by nanosized relaxation spectroscopy N2 - A combination of nanosized dielectric relaxation (BDS) and thermal spectroscopy (SHS) was utilized to characterize the dynamics of thin films of Poly(vinyl methyl ether) (PVME) (thicknesses: 7 nm – 160 nm). For the BDS measurements, a recently designed nano-structured electrode system is employed. A thin film is spin-coated on an ultra-flat highly conductive silicon wafer serving as the bottom electrode. As top electrode, a highly conductive wafer with non-conducting nanostructured SiO2 nano-spacers with heights of 35 nm or 70 nm is assembled on the bottom electrode. This procedure results in thin supported films with a free polymer/air interface. The BDS measurements show two relaxation processes, which are analyzed unambiguously for thicknesses smaller than 50 nm. The relaxation rates of both processes have different temperature dependencies. One process coincidences in its position and temperature dependence with the glassy dynamics of bulk PVME and is ascribed to the dynamic glass transition of a bulk-like layer in the middle of the film. The relaxation rates were found to be thickness independent as confirmed by SHS. Unexpectedly, the relaxation rates of the second process obey an Arrhenius-like temperature dependence. This process was not observed by SHS and was related to the constrained fluctuations in a layer, which is irreversibly adsorbed at the substrate with a heterogeneous structure. Its molecular fluctuations undergo a confinement effect resulting in the localization of the segmental dynamics. To our knowledge, this is the first report on the molecular dynamics of an adsorbed layer in thin films. KW - Broadband dielectric spectroscopy KW - AC-nanochip calorimetry KW - Nanostructured capacitors KW - Thin films PY - 2017 UR - http://pubs.acs.org/doi/pdf/10.1021/acsami.6b14404 DO - https://doi.org/10.1021/acsami.6b14404 SN - 1944-8244 VL - 9 IS - 8 SP - 7535 EP - 7546 PB - ACS Publications CY - Washington DC AN - OPUS4-39291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Juranyi, F. A1 - Kruteva, M. A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Low-Frequency Vibrational Density of States of Nanophase- Separated Poly(n‑alkyl methacrylate)s: Confined Phonons and Relationship to Specific Heat N2 - This study investigates the low-frequency vibrational Density of states of nanophase-separated poly(n-alkyl methacrylate)s (PnMAs) and its relationship to specific heat. This system undergoes a nanophase separation for n > 1 in alkyl side chain-rich domains and a backbone-rich matrix. Using inelastic neutron scattering, the low-frequency vibrational density of states (Boson peak, BP) of PnMAs with varying alkyl side chain lengths (methyl, butyl, hexyl, and octyl) is measured. The results reveal that the BP shifts to higher frequencies with increasing side chain length reaching a maximum. This result indicates a counterbalance of confinement effects and the scattering of the matrix. The behavior of the Boson peak of the PnMAs is compared to other nanophase-separated systems, such as Janus-polynorbornenes and hexakis(n-alkyloxy)triphenylene discotic liquid crystals. The study also explores the connection between the BP and specific heat capacity, showing a linear relationship between the maximum frequency of the BP and the maximum temperature of the specific heat capacity anomaly. Moreover, from the measured vibrational density of states, the specific heat capacity is calculated and compared to experimental results. The comparison reveals qualitative agreement between the calculated and experimental data. These findings provide evidence for the sound wave interpretation of the Boson peak. KW - Inelastic Neutron Scattering PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-636928 DO - https://doi.org/10.1021/acs.macromol.5c00898 SN - 1520-5835 SP - 1 EP - 12 PB - ACS Publications AN - OPUS4-63692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gawek, Marcel A1 - Szymoniak, Paulina A1 - Hülagü, Deniz A1 - Hertwig, Andreas A1 - Schönhals, Andreas T1 - Molecular Mobility of Thin Films and the Adsorbed Layer of Poly(2-vinylpyridine) N2 - The molecular dynamics of thin films and the adsorbed layer of poly(2-vinylpyridine) (P2VP) were investigated using broadband dielectric spectroscopy (BDS) and spectroscopic ellipsometry. Thin films of P2VP were prepared on silicon substrates and characterized to understand the influence of film thickness on the thermal glass transition temperature (Tg) and molecular mobility. The ellipsometric study revealed a decrease in Tg with decreasing film thickness, attributed to the enhanced mobility at the polymer/air interface. The adsorbed layer, prepared via the solvent leaching approach, exhibited a higher Tg compared to the bulk, indicating reduced molecular mobility due to strong polymer substrate interactions. The dielectric measurements were carried out in two different electrode configurations, crossed electrode capacitors (CEC) and nanostructured electrodes (NSE), where the latter allows for a free surface layer at the polymer/air interface. The relaxation rates of the α-relaxation measured in the CEC geometry collapse into one chart independent from the film thickness. For the thin films measured in the NSE arrangement the relaxation rates slow down with decreasing film thickness which was discussed as related to a stronger interaction of the P2VP segments with the native SiO2 at the surface of the silicon substrate compared to aluminum. It is worth to note that the effect of the enhanced mobility at the polymer/air interface is not observed in the dielectric measurements. BDS measurements in NSE geometry identified an additional relaxation process (α*-relaxation) in thin films, which was more pronounced in the adsorbed layer. This process is hypothesized to be related to molecular fluctuations within the adsorbed layer including the adsorption/desorption dynamics of segments or to a Slow Arrhenius Process (SAP) related to the equilibration dynamics deep in the glassy state. KW - Thin polymer films PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637181 DO - https://doi.org/10.1039/d5sm00539f SN - 1744-6848 SP - 1 EP - 12 PB - Royal Society of Chemistry (RSC) AN - OPUS4-63718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Böhning, Martin A1 - Frick, B. A1 - Apple, M. A1 - Mole, R. A. A1 - De Souza, N. R. A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Confined Segmental Diffusion in Nanophase Separated Janus Polynorbornenes as Investigated by Quasielastic Neutron Scattering N2 - A combination of neutron time-of-flight and neutron backscattering spectroscopy was used to investigate the molecular dynamics of Janus polynorbornenes (Janus poly(tricyclononenes)) on a microscopic level. These Janus polynorbornenes, denoted as PTCNSiOR, have a semirigid backbone with −Si(OR)3 side groups attached to it. R represents the length of the alkyl side chain. Here side chain lengths of R = 3 (propyl) and R = 8 (octyl) were considered. It is worth mentioning that these polymers have some potential as active layers in gas separation membranes, especially for the separation of higher hydrocarbons. The combination of time-of-flight and backscattering will ensure a reasonably broad time window for analysis where the incoherent intermediate scattering function SInc(q,t) is considered. Previously, it was shown by X-ray investigations that the system undergoes a nanophase separation into alkyl side chain-rich domains surrounded by a backbone-rich matrix. For PTCNSiOPr (R = 3), the alkyl side-chain-rich domains are truly isolated in the backbone-rich matrix, whereas for PTCNSiOOc (R = 8) these domains percolate through the matrix. Further, it was also previously shown that the alkyl side-chain-rich domains undergo a glass transition. The advantage of neutron scattering experiments discussed here is that besides temporal also spatial information is obtained which will allow conclusions to be drawn about the type of molecular fluctuations. At the lowest measured temperature, the decay in Sinc(q,t) is due to the methyl group rotation. The methyl group dynamics is analyzed in terms of a modified jump-diffusion in a 3-fold potential and yields to a reasonable fraction of hydrogens which contribute to the methyl group rotation. At higher temperatures, the decay in SInc(q,t) is due to both the methyl group rotation and the segmental dynamics in the alkyl side-chain-rich domains. The segmental diffusion is modeled by a sublinear diffusion. For the analysis of the scattering function SInc(q,t) of PTCNSiOPr an elastic scattering due to the immobilized backbone-rich matrix must be taken into account. The analysis reveals that the segmental dynamics is confined by the finite size of alkyl chain-rich domains and that it is intrinsically heterogeneous in nature. Both effects are more pronounced for PTCNSiOPr in comparison to those of PTCNSiOOc. KW - Polynorbornene KW - Quasielastic Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608712 DO - https://doi.org/10.1021/acs.macromol.4c01045 SP - 1 EP - 14 PB - ACS Publications AN - OPUS4-60871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Böhning, Martin A1 - De Souza, N. R. A1 - Juranyi, F. A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Inelastic and Quasielastic Neutron Scattering on Polynorbornenes with Bulky Carbocyclic Side groups N2 - This study investigates the molecular mobility and vibrational properties of polynorbornenes with bulky carbocyclic side groups using inelastic and quasielastic neutron scattering techniques. The polymers, synthesized via metathesis and addition polymerization, exhibit varying degrees of microporosity, which ignificantly influences their gas separation performance. By inelastic neutron scattering experiments, it could be shown that all considered polymers have excess contributions to the low frequency vibrational density of states known as the Boson peak. The maximum frequency of the Boson peak correlates to the microporosity of the polymers. This correlation supports the sound wave interpretation of the Boson peak, suggesting that the microporous structure enhances the compressibility of the material at a microscopic length scale. The molecular mobility, particularly the methyl group rotation, was characterized using elastic scans and quasielastic neutron scattering. The study revealed a temperature dependent relaxation process, with the onset of molecular fluctuations observed around 200 K for the polymer containing methyl groups. For the polymer having no methyl groups only elastic scattering is observed. The methyl group rotation was analyzed in terms of a jump diffusion in a threefold potential with three equivalent energy minima. This leads to an almost correct description of the q dependence of the elastic incoherent scattering function when the number of hydrogen nuclei undergoing the methyl group rotation is considered. It was further evidenced that the fraction of methyl undergoing the methyl group rotation increases with increasing temperature. KW - Polymers of Intrinsic Microporosity KW - Neutron scattering PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630297 DO - https://doi.org/10.1016/j.polymer.2025.128358 SN - 1873-2291 VL - 328 SP - 241 PB - Elsevier Ltd. AN - OPUS4-63029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Malpass-Evans, R. A1 - McKeown, N. A1 - Jalarvo, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Microscopic molecular mobility of high-performance polymers of intrinsic microporosity revealed by neutron scattering – bend fluctuations and signature of methyl group rotation N2 - Polymers of intrinsic microporosity exhibit a combination of high gas permeability and reasonable permselectivity, which makes them attractive candidates for gas separation membrane materials. The diffusional selective gas transport properties are connected to the molecular mobility of these polymers in the condensed state. Incoherent quasielastic neutron scattering was carried out on two polymers of intrinsic microporosity, PIM-EA-TB(CH3) and its demethylated counterpart PIM-EA-TB(H2), which have high Brunauer–Emmett–Teller surface area values of 1030 m2 g-1 and 836 m2 g-1, respectively. As these two polymers only differ in the presence of two methyl groups at the ethanoanthracene unit, the effect of methyl group rotation can be investigated solely. To cover a broad dynamic range, neutron time-of-flight was combined with neutron backscattering. The demethylated PIM-EA-TB(H2) exhibits a relaxation process with a weak intensity at short times. As the backbone is rigid and stiff this process was assigned to bendand-flex fluctuations. This process was also observed for the PIM-EA-TB(CH3). A further relaxation process is found for PIM-EA-TB(CH3), which is the methyl group rotation. It was analyzed by a jump-diffusion in a three-fold potential considering also the fact that only a fraction of the present hydrogens in PIM-EATB(CH3) participate in the methyl group rotation. This analysis can quantitatively describe the q dependence of the elastic incoherent structure factor. Furthermore, a relaxation time for the methyl group rotation can be extracted. A high activation energy of 35 kJ mol-1 was deduced. This high activation energy evidences a strong hindrance of the methyl group rotation in the bridged PIM-EA-TB(CH3) structure. KW - Polymers of Intrinsic Microporosity KW - Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604114 DO - https://doi.org/10.1039/d4sm00520a SP - 1 EP - 11 PB - RSC AN - OPUS4-60411 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Malpass-Evans, R. A1 - McKeown, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Low frequency vibrations and diffusion in disordered polymers bearing an intrinsic microporosity as revealed by neutron scattering N2 - The microscopic diffusion and the low frequency density of states (VDOS) of PIM-EATB(CH3) are investigated by inelastic and quasi-elastic neutron scattering where also the demethylated counterpart of PIM-EA-TB(H2) is considered. These intrinsic microporous polymers are characterized by large BET surface area values of several hundred m2/g and pore sizes between 0.5 and 2 nm. Detailed comparison is made to the archetype of polymers of intrinsic microporosity, PIM-1, and polynorbornenes also bearing a microporosity. Due to the wavelength of neutrons, the diffusion and vibrations can be addressed on microscopic length and time scales. From the inelastic neutron scattering experiments the low frequency density of states (VDOS) is estimated which shows excess contributions to the Debye-type VDOS known as Boson peak. It was found that the maximum frequency of the Boson peak decreases with increasing microporosity characterized by the BET surface area. However, besides the BET surface area, additional factors such as the backbone stiffness govern the maximum frequency of the Boson peak. Further the mean squared displacement related to microscopic motions was estimated from elastic fixed window scans. At temperatures above 175 K, the mean squared displacement PIM-EA-TB(CH3) is higher than that for the demethylated counterpart PIM-EA-TB(H2). The additional contribution found for PIM-EATB(CH3) is ascribed to the rotation of the methyl group in this polymer because the only difference between the two structures is that PIM-EA-TB(CH3) has methyl groups where PIM-EA-TB(H2) has none. A detailed comparison of the molecular dynamics is also made to that of PIM-1 and the microporous polynorbornene PTCNSi1. The manuscript focuses on the importance of vibrations and the localized molecular mobility characterized by the microscopic diffusion on the gas Transport in polymeric separation membranes. In the frame of the random gate model localized fluctuations can open or close bottlenecks between pores to enable the diffusion of gas molecules. KW - Polymer of intrisic microporosity KW - Neutron scattering KW - Boson peak KW - Methyl group rotation PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538490 DO - https://doi.org/10.3390/cryst11121482 VL - 11 IS - 12 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-53849 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed Aejaz A1 - Szymoniak, Paulina A1 - Zorn, R. A1 - Böhning, Martin A1 - Wolff, M. A1 - Zamponi, M. A1 - Schönhals, Andreas T1 - Molecular mobility in high-performance polynorbornenes:A combined broadband dielectric, advanced calorimetry,and neutron scattering investigation N2 - The molecular dynamics of two addition type polynorbornenes, exo-PNBSiand PTCNSi1, bearing microporosity has been investigated by broadbanddielectric spectroscopy, fast scanning calorimetry, and neutron scattering. Bothpolymers have the same side groups but different backbones. Due to theirfavorable transport properties, these polymers have potential applications inseparation membranes for gases. It is established in literature that molecularfluctuations are important for the diffusion of small molecules through poly-mers. For exo-PNBSi, two dielectric processes are observed, which are assignedto Maxwell/Wagner/Sillars (MWS) process due to blocking of charge carriersat internal voids or pore walls. For PTCNSi1, one MWS-polarization process isfound. This points to a bimodal pore-size distribution for exo-PNBSi. A glasstransition for exo-PNBSi and for PTCNSi1 could be evidenced for the first timeusing fast scanning calorimetry. For Tgand the corresponding apparent activa-tion energy, higher values were found for PTCNSi1 compared to exo-PNBSi.For both polymers, the neutron scattering data reveal one relaxation process.This process is mainly assigned to methyl group rotation probably overlayedby carbon–carbon torsional fluctuations. KW - Advanced calorimetry KW - Dielectric spectroscopy KW - Neutron scattering KW - Polynorbornenes PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547086 DO - https://doi.org/10.1002/pen.25995 SN - 0032-3888 VL - 62 IS - 7 SP - 2143 EP - 2155 PB - Wiley AN - OPUS4-54708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Juranyi, Fanni A1 - Böhning, Martin A1 - Zorn, Reiner A1 - Schönhals, Andreas T1 - Low-Frequency Vibrational Density of State of Janus-Polynorbornenes: The Dependence of the Boson Peak on the Nanophase-Separated Structure N2 - Inelastic incoherent neutron time-of-flight scattering was employed to investigate the low-frequency vibrational density of states (VDOSs) for a series of glassy Janus-poly(tricyclononenes), which consist of a rigid main chain and flexible alkyl side chains. Here, the length of the flexible side chains was systematically varied from propyl to octyl. Such materials have potential applications as active separation layers in gas separation membranes as a green future technology, especially for the separation of higher hydrocarbons. From the morphological point of view, the Janus polynorbornenes undergo a nanophase separation into alkyl side chain-rich nanodomains surrounded by a rigid polynorbornene matrix. Here, the influence of the nanophase-separated structure on the low-frequency VDOS is investigated from a fundamental point of view. The low-frequency VDOSs of these Janus polynorbornene show excess contributions to the Debye type VDOS known as the Boson peak (BP) for all side chain lengths. Due to the high incoherent scattering cross-section of hydrogen, most of the scattering comes from the alkyl side chain-rich domains. Compared to conventional glass-forming materials, in the considered Janus polynorbornenes, the BP has a much lower intensity and its frequency position is shifted to higher values. These experimental results are discussed in terms of the nanophase-separated structure where the alkyl chain-rich domains were constrained by the surrounding matrix dominated by the rigid backbone. With increasing alkyl chain length, the size of the alkyl chain-rich domains increases. The frequency position of the BP shifts linearly to lower frequencies with the size of these nanodomains estimated from X-ray measurements. The obtained results support the sound wave interpretation to the BP KW - Inelastic neutron scattering PY - 2023 DO - https://doi.org/10.1021/acs.macromol.3c00913 SN - 0024-9297 SP - 1 EP - 10 PB - ACS AN - OPUS4-57972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Smales, Glen Jacob A1 - Henning, S. A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schönhals, Andreas A1 - Szymoniak, Paulina T1 - Calorimetric and Dielectric Investigations of Epoxy-Based Nanocomposites with Halloysite Nanotubes as Nanofillers N2 - Epoxy nanocomposites are promising materials for industrial applications (i.e., aerospace, marine and automotive industry) due to their extraordinary mechanical and thermal properties. Here, the effect of hollow halloysite nanotubes (HNT) on an epoxy matrix (Ep) was the focus of the study. The structure and molecular mobility of the nanocomposites were investigated using a combination of X-ray scattering, calorimetry (differential (DSC) and fast scanning calorimetry (FSC)) and dielectric spectroscopy. Additionally, the effect of surface modification of HNT (polydopamine (PDA) and Fe(OH)3 nanodots) was considered. For Ep/HNT, the glass transition temperature (Tg) is was de-creased due to a nanoparticle-related decrease of the crosslinking density. For the modified system, Ep/m-HNT, the surface modification resulted in enhanced filler–matrix interactions leading to higher Tg values than the pure epoxy in some cases. For Ep/m-HNT, the amount of interface formed between the nanoparticles and the matrix ranged from 5% to 15%. Through BDS measurements, localized fluctuations were detected as a β- and γ-relaxation, related to rotational fluctuations of phenyl rings and local reorientations of unreacted components. A combination of calorimetry and BDS dielectric spectroscopy revealed a dynamic and structural heterogeneity of the matrix, as confirmed by two glassy dynamics in both systems, related to regions with different crosslinking densities. KW - Rigid amorphous fraction KW - Epoxy nanocomposites KW - Halloysite nanotubes KW - X-ray scattering KW - Differential scanning calorimetry KW - Broadband dielectric spectroscopy KW - Flash DSC PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526668 DO - https://doi.org/10.3390/polym13101634 VL - 13 IS - 10 SP - 1634 PB - MDPI AN - OPUS4-52666 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed A. A1 - Raab, A. R. A1 - Szymoniak, Paulina A1 - Li, Z. A1 - Huber, P. A1 - Laschat, S. A1 - Schönhals, Andreas T1 - Molecular mobility and electrical conductivity of amino acid-based (DOPA) ionic liquid crystals in the bulk state and nanoconfinement N2 - This study explores the molecular mobility, phase behavior, and electrical conductivity of dihydroxyphenylalanine-based ionic liquid crystals (DOPAn, with alkyl side chains n = 12, 14, 16) featuring cyclic guanidiniumchloride headgroups, in both bulk and nanoconfined states. Using broadband dielectric spectroscopy, differential scanning calorimetry, and fast scanning calorimetry, the research uncovers a complex interplay between molecular structure, self-assembly, and molecular mobility. In bulk, DOPAn shows a phase sequence from plastic crystalline to hexagonal columnar and isotropic phases, driven by superdisc formation and columnar organization. Multiple relaxation processes are identified: localized side-chain dynamics (γ-relaxation), ionic headgroup or core motions (α1-relaxation), and cooperative alkyl domain fluctuations (α2-relaxation). Conductivity decreases with increasing side chain length. Under nanoconfinement in anodic aluminum oxide membranes, phase behavior changes: the Colh–Iso transition is suppressed, and a new α3-relaxation appears, linked to dynamics in an adsorbed interfacial layer. DC conductivity drops by up to four orders of magnitude due to confinement effects, altered molecular orientation, and phase transitions—especially the emergence of a nematic-like state in DOPA16. These findings highlight the importance of molecular design, pore geometry, and surface chemistry in tuning ionic liquid crystal properties for advanced applications in nanofluidics, ion transport, and responsive materials. KW - Ionic Liquid Crystals PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639657 DO - https://doi.org/10.1039/d5cp02406d SN - 1463-9084 SP - 1 EP - 17 PB - Royal Society of Chemistry (RSC) AN - OPUS4-63965 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Huang, J. A1 - Szymoniak, Paulina A1 - Bojdys, M. J. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Structure and molecular mobility of phosphinine-based covalent organic frameworks – glass transition of amorphous COFs N2 - Two-dimensional covalent organic frameworks (COFs) based on phosphinine and thiophene building blocks have been synthesized with two different side groups. The materials are denoted as CPSF-MeO and CPSF-EtO where CxxF correspond to the covalent framework, whereas P and S are related to heteroatoms phosphorous and sulfur. MeO and EtO indicate the substituents, i.e. methoxy and ethoxy. Their morphologies were studied by scanning electron microcopy and X-ray scattering. The absence of crystalline reflexes in the X-ray pattern reveal that both materials are amorphous and can be considered as glasses. Furthermore, N2 adsorption measurements indicate substantial Brunauer–Emmett–Teller (BET) surface area values pointing to the formation of three-dimensional pores by stacking of the aromatic 2D layer. An analysis of the porosity of both COFs showed a mean radius of the pores to be of ca. 4 nm, consistent with their chemical structure. The COFs form nanoparticles with a radius of around 100 nm. The thermal behavior of the COFs was further investigated by fast scanning calorimetry. These investigations showed that both COFs undergo a glass transition. The glass transition temperature of CPSF-EtO is found to be ca. 100 K higher than that for CPSF-MeO. This large difference in the glass transition is discussed to be due to a change in the interaction of the COF sheets induced by the longer ethoxy group. It might be assumed that for CPSF-EtO more individual COF sheets assemble to larger stacks than for CPSF-MeO. This agrees with the much larger surface area value found for CPSF-EtO compared to CPSF-MeO. To corroborate the results obtained be fast scanning calorimetry dielectric measurements were conducted which confirm the occurrence of a dynamic glass transition. The estimated temperature dependence of the relaxation rates of the dielectric relaxation and their absolute values agrees well with the data obtained by fast scanning calorimetry. Considering the fragility approach to the glass transition, it was further found that CPSF-MeO is a fragile glass former whereas CPSF-EtO behaves as a strong glass forming material. This difference in the fragility points also to distinct differences in the interaction between the 2D COF molecules in both materials. KW - Covalent Organic frameworks PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596770 DO - https://doi.org/10.1039/d3ma01123b SP - 1 EP - 10 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed Aejaz A1 - Szymoniak, Paulina A1 - Smales, Glen Jacob A1 - Alentiev, D. A1 - Bermeshev, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Molecular Dynamics of Janus Polynorbornenes: Glass Transitions and Nanophase Separation N2 - For the first time, dielectric and calorimetric investigations of an homologous series of Janus polynorbornenes with rigid main backbones and flexible -Si(OR)3 side groups, of differing length alkyl chains (R = Propyl, Butyl, Hexyl, Octyl, Decyl) is reported. Generally, this class of polymers has some potential for applications in the field of gas separation membranes. Two dielectrically active processes are observed at low temperatures, denoted as β- and α- relaxation. The former can be assigned to localized fluctuations, whilst the latter is related to the glassy dynamics of the flexible -Si(OR)3 side groups, creating a nanophase separation in both the alkyl chain rich and backbone rich domains. This is confirmed through temperature modulated DSC measurements and X-ray scattering experiments. The glass transition temperatures of the backbone rich domains, which are beyond or near to their degradation temperatures in terms of conventional DSC, are determined for the first time using Fast Scanning Calorimetry employing both fast heating and cooling rates. This is complimented with scattering experiments that show how the size of the alkyl chain rich domains increases with chain length. Alongside these results, a significant conductivity contribution was observed for all poly(tricyclononenes) with -Si(OR)3 side groups, which is interpreted in terms of a percolation model. KW - Polynorbornenes KW - Broadband Dielectric Spectrscopy KW - Advanced calorimetry PY - 2020 DO - https://doi.org/10.1021/acs.macromol.0c01450 VL - 53 IS - 17 SP - 7410 EP - 7419 PB - ACS AN - OPUS4-51196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schönhals, Andreas A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Böhning, Martin A1 - Zamponi, M. A1 - Frick, B. A1 - Appel, M. A1 - Günther, G. A1 - Russina, M. A1 - Alentiev, D. A1 - Bermeshev, M. A1 - Zorn, R. T1 - Microscopic dynamics of highly permeable super glassy polynorbornenes revealed by quasielastic neutron scattering N2 - The molecular dynamics of addition-type poly(tricyclononenes) with Si-substituted bulky side groups has been investigated by a combination of neutron time-of-flight and neutron backscattering spectroscopy methods on a time scale from 0.1 ps to ca. 3 ns. The investigated poly(tricyclononenes) PTCNSi1 and PTCNSi2g both bear a high microporosity which makes them promising candidates for active separation layers for gas separation membranes. At least for larger gas molecules it is assumed that the pathways for diffusion require an enlargement of pre-existing micropores in terms of an activated zone. A low temperature relaxation process was found for both polymers by the performed neutron scattering experiments. This process was assigned to the methyl group rotation. It was analysed in terms of a jump diffusion in a three-fold potential. The analysis of the dependence of the elastic incoherent structure factor on the scattering vector yields the number of methyl groups which might be immobilized. For PTCNSi1 (3 methyl groups in the monomeric unit) it was found that all methyl groups take part in the methyl group rotation whereas for PTCNSi2g (6 methyl groups in monomeric unit) a considerable number of methyl groups are blocked in their rotation. This immobilization of methyl groups is due to the sterically demanding arrangement of the methyl groups in PTCNSi2g. This conclusion is further supported by the result that the activation energy for the methyl group rotation is three times higher for PTCNSi2g than that of PTCNSi1. KW - Highly permeably polynorbornenes KW - Polymers of intrinsic microporosity KW - Gas separation membranes KW - Quasielastic neutron scattering PY - 2021 DO - https://doi.org/10.1016/j.memsci.2021.119972 SN - 0376-7388 VL - 642 PB - Elesevier B.V. AN - OPUS4-53508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolmangadi, Mohamed Aejaz A1 - Szymoniak, Paulina A1 - Smales, Glen Jacob A1 - Bermeshev, M. A1 - Schönhals, Andreas A1 - Böhning, Martin T1 - Molecular mobility of polynorbornenes with trimethylsiloxysilyl side groups: Influence of the polymerization mechanism N2 - We report dielectric and calorimetric studies on metathesis and addition-type polytricyclononenes, both based on the same monomer bearing three pendant OSiMe3 groups. For the addition-type polymer, dielectric spectroscopy reveals a β*-process related to the microporosity, whereas for its metathesis counterpart, the segmental dynamics manifests as an α-process related to a glass transition. Besides active dielectric processes, a significant conductivity contribution is detected for both samples which for the microporous additiontype polymer is three orders of magnitude greater than for the metathesis polymer. The broadband dielectric spectroscopy is complemented by detailed calorimetric investigations, comprising DSC, FSC, and TMDSC. The calorimetric methods detected the glass transition for the metathesis polymer in agreement with the observed dielectric α-process. Furthermore, the already reported gas transport properties for both polymers are compared, setting them in correlation with the observed molecular mobility and conductivity behavior. The discussed results reflect significant differences in molecular mobility of the two polymers affecting the appearance of microporosity which strongly determines the gas transport properties. KW - Microporous polymers KW - Molecular mobility KW - Electrical conductivity KW - Membrane polymers KW - Gas separation PY - 2022 DO - https://doi.org/10.22079/JMSR.2021.538060.1495 SN - 2476-5406 VL - 8 IS - 3 SP - 1 EP - 9 PB - Membrane Processes Research Laboratory (MPRL) CY - Tehran AN - OPUS4-54303 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Wolf, M. A1 - Alentiev, D. A1 - Bermeshev, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Low frequency vibrational density of state of highly permeable super glassy polynorbornenes – The Boson peak N2 - Inelastic incoherent neutron time-of flight scattering was employed to measure the low frequency density of states for a series of addition polynorbornenes with bulky side groups. The rigid main chain in combination with the bulky side groups give rise to a microporosity of these polymers in the solid state. The microporosity characterized by the BET surfaces area varies systematically in the considered series. Such materials have some possible application as active separation layer in gas separation membranes. All investigated materials show excess contributions to the Debye type density of states characteristic for glasses known as Boson peak. The maximum position of the Boson peak shifts to lower frequency values with increasing microporosity. Data for PIM-1 and Matrimid included for comparison are in good agreement to this dependency. This result supports the sound wave interpretation of the Boson peak. KW - Polynorbornes KW - Neutron Scattering PY - 2020 DO - https://doi.org/10.1039/d0cp03360j SN - 1463-9076 VL - 22 IS - 33 SP - 18381 EP - 18387 PB - Royal Chemical Society AN - OPUS4-51165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kamoun, E. A1 - Afifi, K. A1 - Szymoniak, Paulina A1 - Schönhals, Andreas A1 - Fahmy, Alaa T1 - Structure-property relationship of cross-linked chitosan-ethyl cellulose membranes N2 - Intensive research is focused on creating cost-effective, high-performance polyelectrolyte membranes (PEMs) for electrochemical devices designed to generate and/or store electrical energy. On the other hand, biopolymer materials have been utilized in a wide range of applications across medical and engineering fields, as well as in the textile and energy sectors. Therefore, in this study, chemically cross-linked chito-san/ethyl cellulose-citric acid (CS-EC-CA) membranes were prepared by a casting technique. The structure-property relationship of CS-EC/CA has been discussed based on the molar ratio of CS. The structural properties of the resultant membrane were characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy, thermal stability was assessed using thermogravimetric analysis. Moreover, the ion exchange capacity (IEC) and water uptake of the membrane were studied. FTIR analysis revealed a significant broadening of absorption peaks in the range of 3200–3500 cm-1 , corresponding to -OH groups, presence of CA. A new peak at 1725 cm-1 confirmed the formation of chemical linkages between CA and CS-EC. The results of the thermal analysis revealed that a thermally stable membrane was obtained when it was chemically cross-linked compared to non-cross-linked membranes. The IEC values of the modified membranes were enhanced significantly, increasing from 0.08 mmol/g for pure CS to 0.5 mmol/g for CS (50%) and 0.8 mmol/g for CS (50%) cross-linked withCA. Furthermore, the cross-linked membranes demonstrated the lowest water and ethanol uptake values, emphasizing their suitability for fuel cell applications. KW - Polyelectrolyte membranes PY - 2025 DO - https://doi.org/10.1063/5.0279022 SN - 1089-7666 VL - 37 IS - 8 SP - 1 EP - 11 PB - AIP Publishing AN - OPUS4-63890 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nikitin, D. A1 - Biliak, K. A1 - Protsak, M. A1 - Adejube, B. A1 - Ali-Ogly, S. A1 - Škorvanková, K. A1 - Červenková, V. A1 - Katuta, R. A1 - Tosco, M. A1 - Hanuš, J. A1 - Černochová, Z. A1 - Černoch, P. A1 - Štěpánek, P. A1 - Boiko, O. A1 - Szymoniak, Paulina A1 - Schönhals, Andreas A1 - Faupel, F. A1 - Biedermann, H. A1 - Vahl, A. A1 - Choukourov, A. T1 - Unveiling the Fundamental Principles of Reconfigurable Resistance States in Silver/Poly(ethylene glycol) Nanofluids N2 - Developing novel memristive systems aims to implement key principles of biological neuron assemblies – plasticity, adaptivity, and self-organization – into artificial devices for parallel, energy-efficient computing. Solid-state memristive devices, such as crossbar arrays and percolated nanoparticle (NP) networks, already demonstrate these properties. However, closer similarity to neural networks is expected from liquid-state systems, including polymer melts, which remain largely unexplored. Here, the resistive switching in silver/poly(ethylene glycol) (Ag/PEG) nanofluids, prepared by depositing gas-aggregated Ag NPs into PEGs of varying molecular mass, is investigated. These systems form long-range conductive NP bridges with reconfigurable resistance states in response to an electric field. The zeta-potential of Ag NPs and molecular mobility of PEG determine the prevalence of low resistance (ohmic) state, high resistance states (poor conductance) or intermediate transition states governed by space-charge-limited conduction or electron tunneling. The occurrence of these states is given by the interparticle gaps, which are determined by the conformation of PEG molecules adsorbed on the NPs. It is presented, for the first time, an equivalent circuit model for the Ag/PEG system. These findings pave the way to adopt polymer melts as matrices for neuromorphic engineering and bio-inspired electronics. KW - Nanofluids PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-635351 DO - https://doi.org/10.1002/advs.202505103 VL - 12 SP - 1 EP - 14 PB - Wiley AN - OPUS4-63535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ghasem Zadeh Khorasani, Media A1 - Silbernagl, Dorothee A1 - Szymoniak, Paulina A1 - Hodoroaba, Vasile-Dan A1 - Sturm, Heinz T1 - The effect of boehmite nanoparticles (gamma‐AlOOH) on nanomechanical and thermomechanical properties correlated to crosslinking density of epoxy N2 - We show that complex physical and chemical interactions between boehmite nanoparticles and epoxy drastically affect matrix properties, which in the future will provide tuning of material properties for further optimization in applications from automotive to aerospace. We utilize intermodulation atomic force microscopy (ImAFM) for probing local stiffness of both particles and polymer matrix. Stiff particles are expected to increase total stiffness of nanocomposites and the stiffness of polymer should remain unchanged. However, ImAFM revealed that stiffness of matrix in epoxy/boehmite nanocomposite is significantly higher than unfilled epoxy. The stiffening effect of the boehmite on epoxy also depends on the particle concentration. To understand the mechanism behind property alteration induced by boehmite nanoparticles, network architecture is investigated using dynamic mechanical thermal analysis (DMTA). It was revealed that although with 15 wt% boehmite nanoparticles the modulus at glassy state increases, crosslinking density of epoxy for this composition is drastically low. KW - Crosslinking density KW - Epoxy KW - Intermodulation KW - Atomic force microscopy KW - Nanomechanical properties KW - Boehmite nanoparticles PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-476050 DO - https://doi.org/10.1016/j.polymer.2018.12.054 SN - 0032-3861 SN - 1873-2291 VL - 164 SP - 174 EP - 182 PB - Elsevier AN - OPUS4-47605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waniek, Tassilo A1 - Omar, Hassan A1 - Szymoniak, Paulina A1 - Silbernagl, Dorothee A1 - Sturm, Heinz T1 - The influence of water released from particles in epoxy‐based nanocomposites N2 - AbstractRecent studies have hypothesized that the reinforcing effects of boehmite nanoparticles (BNPs) in polymer nanocomposites (PNCs) are partly related to the particles themselves and partly to the water released from the BNP during curing. In this work, PNCs made from dried BNP (dBNP) with concentrations up to 15 wt% are investigated to differentiate particle and water related effects. The observed trend of the storage modulus in dynamic mechanical thermal analysis measurements was found to be independent of the drying procedure. Stiffness maps from intermodulation atomic force microscopy showed that dBNP leads to a stiffening of the interphase surrounding the particles compared with the unaffected epoxy matrix, while a softer interphase was reported for PNCs with as received BNP. A slight decrease in the glass transition temperature was observed by broadband dielectric spectroscopy related to a lowered crosslink density due to the particles. A significantly higher decrease was reported for PNCs with BNP, attributed to water influencing the curing process. In conclusion, the stiffening of PNC with BNP is related to the particles themselves, while the release of water causes the formation of a soft interphase in the vicinity of the particles and a significant decrease in crosslink density. KW - AFM stiffness of interface KW - Aluminium oxide hydroxide KW - Boehmit nanoparticle KW - Glass transition temperature KW - Broadband dielectric spectroscopy KW - Crosslink density control KW - Structure–property relationship KW - Nanocomposites KW - Thermoset PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-606772 DO - https://doi.org/10.1002/app.55937 SN - 0021-8995 SP - 1 EP - 16 PB - Wiley AN - OPUS4-60677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cano Murillo, Natalia A1 - Szymoniak, Paulina A1 - Smales, Glen Jacob A1 - Sturm, Heinz A1 - Schönhals, Andreas T1 - Electrospun nanocomposites fibers of polycarbonate and taurine modified boehmite nanoparticles - What can be learned from structural and thermal investigations N2 - Though the reinforcing properties of inorganic particles in thermosetting nanocomposites, has been exploited, the integration of nanoparticles continues to be challenging in terms of their homogeneous distribution and their manipulation which can contribute to occupational hazards. Due to a second encapsulations of nanoparticles, electrospun nanocomposite fibers containing nanoparticles might be an alternative for overcoming these issues, as the fiber nonwovens contains the nanoparticles allowing for safer manipulation. Here, the morphology, and the thermal properties of electrospun polycarbonate fibers containing taurine modified boehmite nanoparticles (BNP) are investigated by means of small and wide-angle X-ray scattering as well as fast scanning and temperature modulated fast scanning calorimetry for the first time. The latter techniques allow the investigation of the thermal properties of single fibers at heating rates up to 10^4 K s^-1 keeping its structure intact. A quantitative analysis of the scattering data reveals a porous structure of the fibers. The porous structure is quantified regarding the pore volume and the pore size. A constant amount of aggregation is found even for the highly BNP loaded fibers. Thermal analysis on the fibers reveals a rigid amorphous fraction (RAF) where it is known that RAF determinates the properties of a nanocomposite to a large extent. For the fibers RAF amounts up to 40 wt%, which is essential higher compared to equally formulated PC/BNP composite cast films. The RAF in the case of the fibers, is not only due to the presence of particles in the polymer but also due to orientation effects induced by the electrospinning process. KW - Nanocomposite fibers KW - Electrospinning KW - X-ray scattering KW - Fast scanning calorimetry KW - Rigid amorphous fraction PY - 2021 DO - https://doi.org/10.1021/acsapm.1c01265 VL - 3 IS - 12 SP - 6572 EP - 6585 PB - ACS AN - OPUS4-53871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Elert, Anna Maria A1 - Chen, Yong-Cin A1 - Smales, Glen Jacob A1 - Topolniak, Ievgeniia A1 - Sturm, Heinz A1 - Schönhals, Andreas A1 - Szymoniak, Paulina T1 - Effects of the charge density of nanopapers based on carboxymethylated cellulose nanofibrils investigated by complementary techniques N2 - Cellulose nanofibrils (CNFs) with different charge densities were prepared and investigated by a combination of different complementary techniques sensitive to the structure and molecular dynamics of the system. The morphology of the materials was investigated by scanning electron microscopy (SEM) and X-ray scattering (SAXS/WAXS). The latter measurements were quantitatively analyzed yielding to molecular parameters in dependence of the charge density like the diameter of the fibrils, the distance between the fibrils, and the dimension of bundles of nanofibrils, including pores. The influence of water on the properties and the charge density is studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy. The TGA measurements reveal two mass loss processes. The one at lower temperatures was related to the loss of water, and the second process at higher temperatures was related to the chemical decomposition. The resulting char yield could be correlated to the distance between the microfibrils. The DSC investigation for hydrated CNFs revealed three glass transitions due to the cellulose segments surrounded by water molecules in different states. In the second heating scan, only one broad glass transition is observed. The dielectric spectra reveal two relaxation processes. At low temperatures or higher frequencies, the β-relaxation is observed, which is assigned to localized fluctuation of the glycosidic linkage. At higher temperatures and lower frequencies, the α-relaxation takes places. This relaxation is due to cooperative fluctuations in the cellulose segments. Both processes were quantitatively analyzed. The obtained parameters such as the relaxation rates were related to both the morphological data, the charge density, and the content of water for the first time. KW - Cellulose nanofibrils PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600528 DO - https://doi.org/https://doi.org/10.1021/acsomega.4c00255 SN - 2470-1343 VL - 9 SP - 20152 EP - 20166 PB - ACS AN - OPUS4-60052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silbernagl, Dorothee A1 - Szymoniak, Paulina A1 - Tavasolyzadeh, Zeynab A1 - Sturm, Heinz A1 - Topolniak, Ievgeniia T1 - Multiphoton lithography of interpenetrating polymer networks for tailored microstructure thermal and micromechanical properties N2 - Multiphoton lithography (MPL), an emerging truly 3D microfabrication technique, exhibits substantial potential in biomedical applications, including drug delivery and tissue engineering. Fabricated micro-objects are often expected to undergo shape morphing or bending of the entire structure or its parts. Furthermore, ensuring precise property tuning is detrimental to the realization of the functionality of MPL microstructures. Herein, novel MPL materials based on interpenetrating polymer networks (IPNs) are presented that effectively combine the advantages of acrylate and epoxy systems. IPNs with varying component ratios are investigated for their microfabrication performance and structural integrity with respect to thermal and micromechanical properties. A variety of high-resolution techniques is applied to comprehensively evaluate IPN properties at the bulk, micron, and segmental levels. This study shows that the MPL laser scanning velocity and power, photoinitiator content, and multi-step exposure can be used to tune the morphology and properties of the IPN. As a result, a library of 3D MPL IPN microstructures with high 3D structural stability and tailored thermal and micromechanical properties is achieved. New IPN microstructures with Young’s moduli of 3–4 MPa demonstrate high-to-fully elastic responses to deformations, making them promising for applications in morphable microsystems, soft micro-robotics, and cell engineering. KW - Interpenetrating polymer network KW - Multiphoton lithography KW - Atomic force microscopy KW - Intermodulation AFM KW - Fast scanning calorimetry PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600593 DO - https://doi.org/10.1002/smll.202310580 SN - 1613-6810 SP - 1 EP - 12 PB - Wiley-VCH CY - Weinheim AN - OPUS4-60059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - B, Yang A1 - Chua, Y. Z. A1 - Szymoniak, Paulina A1 - Carta, M A1 - Malpass-Evans, R A1 - McKeown, N A1 - Harrison, W A1 - Budd, P A1 - Schick, C A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Effect of backbone rigidity on the glass transition of polymers of in-trinsic microporosity probed by fast scanning calorimetry N2 - Polymers of Intrinsic Microporosity (PIMs) of high performance have developed as materials with a wide application range in gas separation and other energy-related fields. Further optimization and long-term behavior of devices with PIMs require an understanding of the structure-property relationships including physical aging. In this context the glass transi-tion plays a central role, but with conventional thermal analysis a glass transition is usually not detectable for PIMs be-fore their thermal decomposition. Fast scanning calorimetry provides evidence of the glass transition for a series of PIMs, as the time scales responsible for thermal degradation and for the glass transition are decoupled by employing ultrafast heating rates of tens of thousands K s-1. The investigated PIMs were chosen considering the chain rigidity. The estimated glass transition temperatures follow the order of the rigidity of the backbone of the PIMs. KW - Polymers of intrinsic microporosity KW - Fast scanning calormetry PY - 2019 DO - https://doi.org/10.1021/acsmacrolett.9b00482 SN - 2161-1653 VL - 8 IS - 8 SP - 1022 EP - 1028 PB - ACS Publications AN - OPUS4-48617 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Li, Z. A1 - Wang, D.-Y. A1 - Schoenhals, Andreas T1 - Dielectric and flash DSC investigations on an epoxy based nanocomposite system with MgAl layered double hydroxide as nanofiller N2 - Nanocomposites based on MgAL layered double hydroxides (LDH) and an epoxy resin were prepared and investigated by a combination of complementary methods. As epoxy resin Bisphenol A diglycidyl ether (DGEBA) was used with Diethylenetriamine as curing agent. The LDH was modified with taurine, which acts as an additional crosslinking agent due to its amine groups. The epoxy resin was cured in a presence of the nanofiller, which was added to the system in various concentrations. X-ray scattering, by combination of SAXS and WAXS was used to characterize the morphology of the obtained nanocomposites. These investigations show that the filler is distributed in the matrix as small stacks of ca. 10 layers. The molecular dynamics of the system, as probe for structure, was investigated by broadband dielectric spectroscopy. In addition to the - and -relaxation (dynamic glass transition), characteristic for the unfilled materials, a further process was found which was assigned to localized fluctuations of segments physically adsorbed or chemically bonded to the nanoparticles. The dielectric -relaxation is shifted to higher temperatures for the nanocomposites in comparison to the pure material but depends weakly on the content of nanoparticles. Further, for the first time Flash DSC was employed to a thermosetting system to investigate the glass transition behavior of the nanocomposites. The heating rates were converted in to relaxation rates. For low concentrations of the nanofiller the thermal data overlap more or less with that of the pure epoxy. For higher concentrations the thermal data are shifted significantly to higher temperatures. This is discussed in terms the cooperativity approach to the glass transition. KW - Nanocomposites KW - Broadband dielectric spectroscopy KW - Flash DSC PY - 2019 DO - https://doi.org/10.1016/j.tca.2019.01.010 SN - 0040-6031 VL - 677 SP - 151 EP - 161 PB - Elsevier AN - OPUS4-48218 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Madkour, Sherif A1 - Schönhals, Andreas T1 - Molecular dynamics of the asymmetric blend PVME/PS revisited by broadband dielectric and specific heat spectroscopy: Evidence of multiple glassy dynamics N2 - The molecular mobility of the highly asymmetric miscible blend poly(vinyl methyl ether)/polystyrene was investigated by broadband dielectric (frequency range 10^-1 Hz – 10^9 Hz) and specific heat spectroscopy (frequency range 10^1 Hz – 10^4 Hz). The dielectric spectra revealed a complex molecular dynamic behavior, where three different relaxation processes were observed. At temperatures below the glass transition temperature an α´-relaxation was found, with an Arrhenius-like temperature dependence of its relaxation rates. It is assigned to localized fluctuations of the confined PVME segments within a frozen glassy matrix dominated by PS. Above the thermal glass transition temperature two processes with a VFT behavior of their relaxation rates were detected called α1- and α2-relaxation, both originating from PVME dipoles fluctuating in PS-rich environments, however with diverse PS concentrations. The relevant length scales for the processes are assumed to be different, corresponding to the Kuhn segment length for the former relaxation and to the CRR for the latter one. The observed multiple glassy dynamics result from spatial local compositional heterogeneities on a microscopic level. Additionally, SHS investigations were performed for the first time for this system, proving an existence of a fourth relaxation process (α3-relaxation) due to the cooperative fluctuations of both PS and PVME segments. The separation between the thermal α3- and dielectric α2-relaxation increases dramatically with increasing polystyrene concentration, proving that the thermal response is dominated by PS. KW - Polymer blends KW - Dynamic heterogeneity KW - Broadband dielectric spectroscopy KW - Specific heat spectroscopy PY - 2019 DO - https://doi.org/10.1021/acs.macromol.8b02697 SN - 0024-9297 VL - 52 IS - 4 SP - 1620 EP - 1631 PB - ACS Publications AN - OPUS4-47516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gawek, Marcel A1 - Madkour, Sherif A1 - Szymoniak, Paulina A1 - Radnik, Jörg A1 - Schönhals, Andreas T1 - Energy Dependent XPS Measurements on Thin Films of a Poly(vinyl methyl ether)/Polystyrene Blend in Dependence on Film Thickness – Concentration Profile on a Nanometer Resolution to Understand the Behavior of Nanofilms N2 - The composition of the surface layer in dependence from the distance of the polymer/air interface in thin films with thicknesses below 100 nm of miscible polymer blends in a spatial region of a few nanometers is not investigated completely. Here, thin films of the blend poly vinyl methyl ether) (PVME)/polystyrene (PS) with a composition of 25/75 wt% are investigated by Energy Resolved X-ray Photoelectron Spectroscopy (ER-XPS) at a synchrotron storage ring using excitation energies lower than 1 keV. By changing the energy of the photons the information depth is varied in the range from ca. 1 nm to 10 nm. Therefore, the PVME concentration could be estimated in dependence from the distance of the polymer/air interface for film thicknesses below 100 nm. Firstly, as expected for increasing information depth the PVME concentration decreases. Secondly, it was found that the PVME concentration at the surface has a complicated dependence on the film thickness. It increases with decreasing film thickness until 30 nm where a maximum is reached. For smaller film thicknesses the PVME concentration decreases. A simplified layer model is used to calculate the effective PVME concentration in the different spatial regions of the surface layer. KW - Energy dependent XPS KW - Soft X-ray KW - Thin films PY - 2021 DO - https://doi.org/10.1039/d1sm00656h VL - 17 IS - 29 SP - 6985 EP - 6994 PB - The Royal Chemical Society AN - OPUS4-53039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madkour, Sherif A1 - Szymoniak, Paulina A1 - Radnik, Jörg A1 - Schönhals, Andreas T1 - Unraveling the Dynamics of Nanoscopically Confined PVME in Thin Films of a Miscible PVME/PS Blend N2 - Broadband dielectric spectroscopy (BDS) was employed to investigate the glassy dynamics of thin films (7−200 nm) of a poly(vinyl methyl ether) (PVME)/polystyrene (PS) blend (50:50 wt %). For BDS measurements, nanostructured capacitors (NSCs) were employed, where films are allowed a free surface. This method was applied for film thicknesses up to 36 nm. For thicker films, samples were prepared between crossed electrode capacitors (CECs). The relaxation spectra of the films showed multiple processes. The first process was assigned to the α-relaxation of a bulklike layer. For films measured by NSCs, the rates of α-relaxation were higher compared to those of the bulk blend. This behavior was related to the PVME-rich free surface layer at the polymer/air interface. The second process was observed for all films measured by CECs (process X) and the 36 nm film measured by NSCs (process X2). This process was assigned to fluctuations of constraint PVME segments by PS. Its activation energy was found to be thickness-dependent because of the evidenced thickness dependency of the compositional heterogeneity. Finally, a third process with an activated temperature dependence was observed for all films measured by NSCs (process X1). It resembled the molecular fluctuations in an adsorbed layer found for thin films of pure PVME, and thus, it is assigned accordingly. This process undergoes an extra confinement because of frozen adsorbed PS segments at the polymer/substrate interface. To our knowledge, this is the first example where confinement-induced changes were observed by BDS for blend thin films KW - Thin Films KW - Broadband Dielectric Spectroscopy PY - 2017 DO - https://doi.org/10.1021/acsami.7b10572 SN - 1944-8244 VL - 9 IS - 42 SP - 37289 EP - 37299 PB - ACS Publications AN - OPUS4-42652 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leng, Jing A1 - Szymoniak, Paulina A1 - Kang, N.-J. A1 - Wang, D-Y A1 - Wurm, A. A1 - Schick, C. A1 - Schönhals, Andreas T1 - Influence of interfaces on the crystallization behavior and the rigid amorphous phase of poly(l-lactide)-based nanocomposites with different layered doubled hydroxides as nanofiller N2 - Based on the three-phase model of semi-crystalline polymers, we determined all phase fractions of the NiAl-LDH/PLLA nanocomposites in dependence on the concentration of the nanofiller. Moreover, the rigid amorphous fraction (RAF) was separated into the RAFcrystal and the RAFfiller unbiasedly. A detailed comparison to the related nanocomposite system MgAl-LDH/PLLA was made considering that Mg and Ni have different atomic weights. As a first result is was found that NiAl-LDH/PLLA displays a higher crystallization rate compared to MgAl-LDH/PLLA, which is related to the different morphologies of the two nanocomposite systems. For both systems RAFcrystal increases with increasing concentration of the nanofiller. This means in the case of the nanocomposite not each crystal produces the same amount of RAF, as often assumed. Also, RAFfiller increases with the concentration for both systems but in a different way. This is discussed considering again the different morphologies of both nanocomposites. KW - Polymer-based nanocomposites KW - Temperature modulated differential scanning calorimetry PY - 2019 DO - https://doi.org/10.1016/j.polymer.2019.121929 VL - 184 SP - 121929 PB - Elesevier Ltd. AN - OPUS4-49557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szymoniak, Paulina A1 - Gawek, Marcel A1 - Madkour, S. A1 - Schönhals, Andreas T1 - Confinement and localization effects revealed for thin films of the miscible blend Poly(vinyl methyl ether) / Polystyrene with a composition of 25/75 wt% N2 - Thin films (200-7nm) of the asymmetric polymer blend poly(vinyl methyl ether) (PVME)/polystyrene (PS) (25/75wt%) were investigated by broadband dielectric spectroscopy (BDS). Thicker samples ([Formula: see text]37 nm) were measured by crossed electrode capacitors (CEC), where the film is capped between Al-electrodes. For thinner films ([Formula: see text]37 nm) nanostructured capacitors (NSC) were employed, allowing one free surface in the film. The dielectric spectra of the thick films showed three relaxation processes ( [Formula: see text] -, [Formula: see text] - and [Formula: see text] -relaxation), like the bulk, related to PVME fluctuations in local spatial regions with different PS concentrations. The thickness dependence of the [Formula: see text] -process for films measured by CECs proved a spatially heterogeneous structure across the film with a PS-adsorption at the Al-electrodes. On the contrary, for the films measured by NSCs a PVME segregation at the free surface was found, resulting in faster dynamics, compared to the CECs. Moreover, for the thinnest films ([Formula: see text]26 nm) an additional relaxation process was detected. It was assigned to restricted fluctuations of PVME segments within the loosely bounded part of the adsorbed layer, proving that for NSCs a PVME enrichment takes place also at the polymer/substrate interface. KW - Thin polymer films KW - Broadband dielectric spectroscopy PY - 2019 DO - https://doi.org/10.1140/epje/i2019-11870-3 SN - 1292-895X VL - 42 IS - 8 SP - 101, 1 EP - 11 PB - Springer AN - OPUS4-48651 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gawek, Marcel A1 - Omar, Hassan A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Growth kinetics of the adsorbed layer of poly(2-vinylpyridine) - An indirect observation of desorption of polymers from substrates N2 - The growth kinetics of the adsorbed layer of poly(2-vinylpiridine) on silicon oxide is studied using a leaching technique which is based on the Guiselin brushes approach. The adsorbed layer is grown from a 200 nm thick P2VP film for several annealing time periods at different annealing temperatures. Then the film is solvent-leached, and the height of the remaining adsorbed layer is measured by atomic force microscopy. At the lowest annealing temperature only a linear growth regime is observed, followed by a plateau. Here, the molecular mobility of segments is too low to allow for a logarithmic growth. At higher annealing temperatures, both linear and logarithmic growth regimes are observed, followed by a plateau. At even higher annealing temperatures, the growth kinetics of the adsorbed layer changes. A linear growth followed by logarithmic growth kinetics is observed for short annealing time periods. For longer annealing time periods, an upturn of the growth kinetics is observed. At the highest annealing temperature, only a logarithmic growth regime is found. The change in the growth kinetics is discussed by an alteration in the structure of the adsorbed layer. Moreover, the interaction between the polymer segments and the substrate becomes weaker due to both enthalpic and entropic effects. Therefore, at high annealing temperatures the polymer segments might more easily desorb from the substrate. KW - Ultra thin polymer films PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575423 DO - https://doi.org/10.1039/d3sm00129f SN - 1744-683X SN - 1744-6848 VL - 19 IS - 21 SP - 3975 EP - 3982 PB - Royal Society of Chemistry (RSC) CY - London AN - OPUS4-57542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fahmy, A. A1 - Anis, B. A1 - Szymoniak, Paulina A1 - Altmann, Korinna A1 - Schönhals, Andreas T1 - Graphene Oxide/Polyvinyl Alcohol–Formaldehyde Composite Loaded by Pb Ions: Structure and Electrochemical Performance N2 - An immobilization of graphene oxide (GO) into a matrix of polyvinyl formaldehyde (PVF) foam as an eco-friendly, low cost, superior, and easily recovered sorbent of Pb ions from an aqueous solution is described. The relationships between the structure and electrochemical properties of PVF/GO composite with implanted Pb ions are discussed for the first time. The number of alcohol groups decreased by 41% and 63% for PVF/GO and the PVF/GO/Pb composite, respectively, compared to pure PVF. This means that chemical bonds are formed between the Pb ions and the PVF/GO composite based on the OH groups. This bond formation causes an increase in the Tg values attributed to the formation of a strong surface complexation between adjacent layers of PVF/GO composite. The conductivity increases by about 2.8 orders of magnitude compared to the values of the PVF/GO/Pb composite compared to the PVF. This means the presence of Pb ions is the main factor for enhancing the conductivity where the conduction mechanism is changed from ionic for PVF to electronic conduction for PVF/GO and PVF/GO/Pb. KW - Graphene oxide KW - Polyvinyl formaldehyde KW - Lead ions KW - Conductivity PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-549588 DO - https://doi.org/10.3390/polym14112303 SN - 2073-4360 VL - 14 IS - 11 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-54958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raab, A. R. A1 - Grießler, T. R. A1 - Rück, D. A1 - Li, Z. A1 - Zens, A. A1 - Bruckner, J. R. A1 - Huber, P. A1 - Schönhals, Andreas A1 - Szymoniak, Paulina A1 - Laschat, S. T1 - Salt complexation drives liquid crystalline selfassembly in crown ether–amino acid hybrids N2 - Crown ether–amino acid hybrids represent a promising class of amphiphilic molecules combining ion recognition with self-assembly capabilities. Despite extensive studies on their binding properties, the influence of inorganic salt complexation on their liquid crystalline behaviour remains underexplored. Here we synthesized amphiphilic [18]-crown-6 derivatives of L-dihydroxyphenylalanine and tetrahydroisoquinoline analogues, systematically investigating the effects of alkyl chain length and salt type on mesophase formation. Complexation with various salts induced liquid crystalline phases, transitioning from smectic A to columnar hexagonal structures as anion size and alkyl chain length increased. Structural analyses and electron density mapping revealed assembly into charged superdiscs forming columnar stacks with tunable ion channels. Broadband dielectric spectroscopy highlighted differences in molecular mobility and conductivity linked to molecular design. These findings establish salt complexation as a key strategy to control self-assembly and ion transport in crown ether–amino acid hybrids, advancing their potential in responsive soft materials and ion-conductive applications. KW - Ionic liquid crystals PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655986 DO - https://doi.org/10.1039/d5tc04129e SP - 1 EP - 18 PB - Royal Society of Chemistry (RSC) AN - OPUS4-65598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dudziak, Mateusz A1 - Riechers, Birte A1 - Maaß, Robert A1 - Michalchuk, Adam A1 - Schönhals, Andreas A1 - Szymoniak, Paulina T1 - Beyond conventional calorimetry: Unlocking thermal characterization with fast scanning techniques N2 - Fast scanning calorimetry (FSC) has emerged as a transformative technique in thermal analysis, enabling the investigation of rapid and kinetically driven thermal transitions that are inaccessible to conventional differential scanning calorimetry. This review highlights the capabilities enabled by FSC for studying a wide range of materials under extreme thermal conditions, including polymers, pharmaceuticals, metallic glasses, nanocomposites, and hydrogels. By employing ultrafast heating and cooling rates, FSC allows for the suppression of crystallization, resolution of weak transitions, and analysis of thermally labile or size-limited samples. The technique is particularly valuable for probing glass transitions, relaxation phenomena, and phase behavior in systems with complex morphologies or confined geometries. Case studies demonstrate the use of FSC in characterizing vitrification, physical aging, and interfacial dynamics, as well as its application in emerging fields such as additive manufacturing, supramolecular systems, and neuromorphic materials. Together, these examples underscore the role that FSC plays in advancing the understanding of structure-property relationships across diverse material classes. KW - Flash DSC KW - Calorimetry KW - Glass transition PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647405 DO - https://doi.org/10.1016/j.tca.2025.180177 VL - 754 SP - 1 EP - 14 PB - Elsevier B.V. AN - OPUS4-64740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Linberg, Kevin A1 - Szymoniak, Paulina A1 - Schönhals, Andreas A1 - Emmerling, Franziska A1 - Michalchuk, Adam T1 - The Origin of Delayed Polymorphism in Molecular Crystals Under Mechanochemical Conditions N2 - We show that mechanochemically driven polymorphic transformations can require extremely long induction periods, which can be tuned from hours to days by changing ball milling energy. The robust design and interpretation of ball milling experiments must account for this unexpected kinetics that arises from energetic phenomena unique to the solid state. Detailed thermal analysis, combined with DFT simulations, indicates that these marked induction periods are associated with processes of mechanical activation. Correspondingly, we show that the pre‐activation of reagents can also lead to marked changes in the length of induction periods. Our findings demonstrate a new dimension for exerting control over polymorphic transformations in organic crystals. We expect mechanical activation to have a much broader implication across organic solid‐state mechanochemistry. KW - General Chemistry KW - Catalysis KW - Organic Chemistry PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-589219 DO - https://doi.org/10.1002/chem.202302150 SN - 0947-6539 SP - e202302150 PB - Wiley AN - OPUS4-58921 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krause, Christina A1 - Szymoniak, Paulina A1 - Lohstroh, W. A1 - Juranyi, F. A1 - Zamponi, M. A1 - Frick, B. A1 - Al-Sabbagh, Dominik A1 - Emmerling, Franziska A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Complex molecular dynamics of symmetric model discotic liquid crystals: Comparison of Hexakis(hepta-alkanoyloxy)triphenylene (HOT6) with Hexakis(hexa-alkyloxy)triphenylene (HAT6) N2 - This study investigates the complex molecular dynamics of discotic liquid crystals (DLCs) by comparing two structurally similar compounds: Hexakis(hepta-alkanoyloxy)triphenylene (HOT6) and Hexakis(hexa-alkyloxy)triphenylene (HAT6) having the same triphenyl core and the same length of the alkyl side chain. The difference of both materials is that the alkyl chain is linked by an oxygen bridge to the triphenylene core for HAT6 and by a ester group for HOT6. Using a combination of broadband dielectric spectroscopy, differential scanning calorimetry, X-ray scattering, and neutron scattering techniques, the research explores the glass transition phenomena and relaxation processes in these materials. HOT6, featuring ester linkages, exhibits distinct dynamic behavior compared to HAT6, including two separate glass transitions indicated by the 1- and 2-relaxation found by dielectric spectroscopy which are assigned to the glassy dynamics of the alkyl side chain in the intercolumnar space and that of the columns, respectively. The study reveals that the ester group in HOT6 leads to increased molecular rigidity and altered packing in the intercolumnar space, as evidenced by X-ray scattering and the vibrational density of states. Neutron scattering confirms localized methyl group rotations and a further relaxation process which relates to the -relaxation revealed by dielectric spectroscopy. The findings contribute to a deeper understanding of glassy dynamics in partially ordered systems and highlight the influence of molecular architecture on relaxation behavior in DLCs. KW - Discotic Liquid Crystals PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655171 DO - https://doi.org/10.1039/d5sm01247c SN - 1744-6848 SP - 1 EP - 17 PB - Royal Society of Chemistry (RSC) AN - OPUS4-65517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Saeed, A. M. A1 - Saied, M. A. A1 - Szymoniak, Paulina A1 - Altmann, Korinna A1 - Schönhals, Andreas A1 - Fahmy, Alaa T1 - High performance novel polyelectrolyte membrane consisting of polyvinyl alcohol-phenylsilanol-polypyrrole N2 - The synthesis of composite membranes based on PVA, PPy, and sulfonated–hydrolyzed TMPS was investigated for application in proton–exchange membrane fuel cells. FT–IR confirmed the hydrolysis of TMPS through the appearance of Si–OH vibrations, disappearance of Si–O–CH3 bands, reduced CH3 stretching intensity (2840 cm− 1), and successful sulfonation of the phenyl ring (1030 cm− 1). XPS verified the introduction of sulfonic acid groups by identifying S2p peaks between 166–170 eV. Scanning electron microscopy (SEM) showed an incorporation of PPy and that the membrane morphology altered by silanol leading to an increased surface roughness and inducing phase separation in comparison to pure PVA. The PVA–PPy–Si membrane which did not undergo phase separation demonstrated improved mechanical stability (maximum stress 5.91 MPa), reduced methanol uptake (22%, lower than Nafion’s 30%), and enhanced thermal resistance compared to PVA–PPy and PVA–Si. It also exhibited a high ion–exchange capacity (1.5mmol g− 1, exceeding Nafion® at 0.9mmol g− 1 ) and a proton conductivity of 0.036 S/cm, twice that of Nafion 117. These combined properties identify the PVA–PPy–Si composite as a promising high–performance polyelectrolyte membrane for fuel cell applications. KW - Polyelectrolyte membrane PY - 2026 DO - https://doi.org/10.1016/j.apsusc.2026.166495 SN - 1873-5584 VL - 731 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-65627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -